Method of locking together metal sheets



Spt. 4l2, 1933.

F. E. NEWTON METHOD Of' LOCKING TOGETHER METAL' SHEETS Filed Aug. 22. 1931 Panarea sept. 412,1933

METHOD OF LOCKING TOGETHER METAL SHEETS `Frank E. Newton, Hartford, Conn.

Application August 22, 1931. Serial No. 558,760

This invention relates to improvements in the art oi locking together a plurality of sheets of iron, steel, brass, copper or aluminum, or locking such sheets to a body of stiiiening or sup- I portingmaterial, either wood or metal.

' The object of the invention' is to provide a simple method whereby sheets of metal may easily be tightly locked together or firmly locked to a body by means of a common, unhardened screw of the ordinary wood screw type, without requiring the cutting of any threads in the parts to be secured.

In attaining this end, an opening that is angular in cross section is punched in the superposed metallic sheets to be fastened so as to remove a portion of the metal and at the same time produce nested tongues that project out o! the plane of the sheets from the `sides of the opening, and turning a common wood screw through the opening, the relative sizes of the opening and the root of the screw being such that the threads of the screw will force their way through .the opening, expanding the tongues, and when set, the tongues will engage the threads after the manner oi spring pawls and will resist all strains or forces which would tend to separate the sheets that are thuslocked together. With this construction the threads do not cut into the metal when the screws are turned through the openings, and thus it is unnecessary to harden the screws or the screw threads, and the engagement of the tongues with the threads is such that the greater the strains or forces tending to separate the locked parts, the stronger will be the bite or hold of the tongues against the threads to resist the separation of the parts.

lurthermcre,V- with angular punchings and tongues the edges of the openings nest together in such away as to prevent any movement or 4o turning of the sheets relative to each other in the plane of their surfaces, as is possible with round punched holes having burred edges, and thus eliminate the possibility oi vibration loosening the screw. In the accompanying drawing,

Fig. l shows `a plan of the metal sheets with a square hole punched through them. Fig. 2 is a section through the sheets showing the tongues which result from the punching operation. Fig. B is a bottom view of the sheets with the square hole looking toward the tongues. Fig. 4 is a sectional view through the punched sheets, and a block oi* wood, locked together by a common double thread wood screw. Fig. 5, on greatly enlargecl scale, illustrates the manner in which the tongues of the parts to be fastened engage the threads of the fastening screw and lock the parts together. Fig. 6 is a plan of the sheets with a triangular hole punched through them, as is preferable when a triple thread locking screw is to be used. Fig. 'I is a section of the sheets taken across the triangular hole. Fig. 8 is a bottom view of the sheets with the -triangular hole looking toward the tongues. Fig. 9 is a sectional view through the sheets with a triangular hole G5 and three tongues locked together by a triple thread screw. Fig. l0, on a greatly enlarged scale, illustrates the manner of engagement o! the spring tongues, when a triangular hole'is punched through the sheets, with the threads oi a triple thread screw. Fig. 11 shows a punch' thatmay be used for forming a square hole and four locking tongues. Fig. 12 shows a punch that may be used for forming a triangular hole and three locking tongues.

In the practice of the invention first illustrated', two sheets of relatively thin metal, l and 2, are placed one upon the other and a rectangular hole Bismade through them by a punch 4. The punch is shaped to cut a small section of metal from the sheets and depress the edges of the opening so as to form four distinct and individual tongues 5 on each sheet. These tongues are` integral with the edges of the openings through the respective sheets and those of the upper sheet are g5 nested in those of the lower sheet.

A screw 6, which may have a head ci any common shape as the head is not relied upon to lock the parts together, is turned through the opening thus formed in the sheets. The screw illustrated in connection with the sheets having a rectangular opening is a common, double thread, 'unhardened wood screw.

The punch 4 has a tapered end 7 that at the tip has a cross sectional area which is substantially one half the diameter of the root of the screw to be used, and that increases from that size to substantially the major diameter ci the screw. A punch thus shaped removes the reu quired amount oi metal i'rom the sheets and clepresses the metal remaining about the opening so as to produce the tongues. The upper area of, the opening thus made is of a size which will ren ceive the threads of the screw without requiring the threads to cut into the metal of the sheets as the screw is turned in, and the tongues project inwardly toward each other leaving a space ha tween the opposite tongues that is substantially equal to the diameter of the'root of the screw. When the screw is turned through this opening U0 Cil pawls engaging with ratchet teeth. The tongues yield outwardly as the threads pass them but spring inward so as to engage the threads andv tightly pressaganst the body o! the screw.

With a rectangular opening and a double thread screw, at least two opposite tongues will engage threads, one tongue engaging with one thread and the opposite tongue engaging with the other thread. The threads on the screw may be cut close to the under side of its head, as shown in Fig. 10, but when the sheets are to be locked together and held against a. stiiening or supporting structure 8, as illustrated in Fig. 4, it is not necessary to so thread the screw. `It is adventageous to have the distance apart of the screw threads approximately the same as the thickness of the sheets of metal to he leckedtogether,

Any force which tends to separate the metal sheets thus locked causes the ends 'of `the tongues to contract and increase their bite against the threads and root of the screw. The nested tongues being rectangular restrain the sheets from twisting relatively to each other in the plsnelof their surfaces and thus working loose or causing the screw to work out.

' in the second' method illustrated, the metal sheets ll and l2 are laid one upon the other and perforated. with s triangular punch 13. This punch has a tapered end so sized and shaped es to cut away a small section ofnietnl and leave a triangular opening 14 with three nested com verging tongues 15 integral with the edge of the opening through each sheet. With this form of onening e triple thread, unherdened wood screw i8 is preferably employed. When such a screw is turned through the triangular opening the tongues yield to permit the passage of the threads without requiring them to out into the metal.. anni then the tongues spring inward so tiint their ends engage the sides of the respective threfns sind hito against the threads and root of the und tightly lock the screw in piece. fr s in ce rst mentioned any tendency oi the sheets to separate causes-the tongues to contract and more tightly bite against the screw. While double and triple thread screws have been mentioned, single thread screws may be used if desired. l

The invention claimed iszl. The method of locking together relatively thin sheets of metal, which comprises laying the -sheets one upon the other and with an angular shearing punch cutting metal from and forming an angular opening through said sheets and slitting the metal back from the angles of said opening and bending the slitted sections to produce uniform nested tongues with'straight ends on each side of said angular opening, and subsequently threading a screw through said opening and causing the engagement of the ends of said tongues with threads of the screw.

2. The method of locking together relatively' thin sheets of metal, which comprises laying the sheets one upon the other and with a square shearing punch cutting metal from and forming a square opening through said sheets and slitting the metal hack from the cornersv of said opening and bending the slitted sections to produce uni form nested tongues with straight ends on each side of said square opening, and subsequently threading a screw through said opening sind causing the engagement of the enpt said tongues withtnreads of the screw.

3. The method of lockin'gtogether relatively thin sheets of metal, which comprises laying the sheets one upon the other and with a triangular shearing punch cutting metal from and forming n triangular opening through said sheets and slitting the metal back from the angles of said opening and bending the slitted sections to produce uniform nested tongues with straight ends on each side of seid triangular opening, and subsequently threading a screw through said opening and causing the engagement of the ends of seid tongues with threads oi' the screw.

resins: E. NEWTON.-

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